The present disclosure relates to electronic devices, and more particularly, to an electronic device having a multi-mode acoustic system and a method for radiating sound waves.
Electronic devices such as cellular telephones, pagers, personal digital assistants (PDAs), handheld computers, micro-cassette or digital voice recorders, and two-way radios are usually designed with compactness and portability in mind. For example, some cellular telephones are constructed with two portions that fold clamshell-like to conserve space. This design allows the designer to provide multiple modes of operation (e.g., voice message retrieval and voice call origination) in a compact package. In particular, these cellular telephones may include a top portion and a base portion that are rotatably coupled together. Typically, the top portion may include a speaker to convert electrical signals into sound waves in the human-audible frequency range of 20 Hertz (Hz) to 20,000 kilo-Hertz (klz), and ports to emanate the sound waves. Different modes may be available in an open position and in a closed position. For example, a user of a cellular telephone may be able to retrieve a voice message and/or to answer an incoming call with the phone in the open position (i.e., the device is flipped open with the top portion rotated away from the base portion) by placing the speaker adjacent to the user""s ear to listen. Although the user may be able to hear sound waves emitted by the speaker when the phone is in the closed position (e.g., phone ring indicating of an incoming call), the user may not be able to retrieve the voice message and/or to answer the incoming call in the closed position. Because the speaker may produce different acoustic frequency responses and amplitudes in the open position and in the closed position, the user may need a set of headphones to operate the same modes when the phone is in the closed position that may be heard through the speaker in the open position (e.g., either to answer or to initiate a voice call). Separate audio paths may be implemented into the phone to provide substantially identical acoustical response in both the open position and the closed position. However, such a design would deteriorate the leak tolerance of the phone (i.e., the seal between the phone and the user""s ear) for optimal performance. That is, the air leakage between the phone and the user""s ear may cause reproduction of low frequency sound to decrease. As phones reduce in size, the amount of air leakage increases because the contact area between the phone and the user""s ear is smaller. Although a switched path design may produce an identical output signal in either the open position or the closed position, the leak tolerance may also suffer without a seal formed by the user""s ear. Further, the switched path design may require additional moving parts to the phone and increase cost to manufacture it.
To achieve optimal performance, some cellular telephones may need to be oriented in a particular position. For example, a credit-card size cellular telephone may obtain better reception with the antenna being farthest away from the user""s head. The antenna may be disposed within the phone such that the phone may achieve optimal performance when oriented side ways against the user""s head. However, the speaker is typically placed in the front-face of the phone such that the user may place the front-face of the phone against the user""s ear to listen. Because of the orientation of the antenna and the speaker, the user may not be able to achieve optimal reception and audio quality.
Therefore, a need exists for an acoustic system within an electronic device to provide acceptable audio quality in a variety of modes using the same speaker.